In the existing technology, there is a wide variety of documents relating to drilling fluids and related materials.
It is known that drilling fluid, also referred to as drilling mud, is an important part of a drilling operation. The fluid is important to effect transport of debris, undesirable materials, gas etc. The fluid also functions to maintain lubrication and act as a coolant of the drill bit which experiences enormous force, friction and other stresses.
Typical of the presently used fluids is Kim Mud (a blend of polysaccharide polymers, calcium carbonate, calcium lignosulfonate). This material provides high carrying capacity by an inherent thixotropic viscosity. The composition may contain potassium ions for redncing volume increases (swelling). This has the advantage of preventing hydration of moisture sensitive clays.
D-limonene has also been used in drilling fluid and is particularly favored in view of the fact that it is a natural substance extracted from citrus rind.
Various amines have also been used to augment drilling fluid and provide a variety of advantages in different operating conditions.
It would be desirable to have a fluid capable of cleaning tar out of sand and incorporate the oil in an emulsion with subsequent release. Most of the fluids in current use are based upon preventing the tar (heavy oil) from entering the mud.